High-rate properties of LiFePO_4/carbon composites as cathode materials for lithium-ion batteries

摘要

Electrochemical properties of LiFePO_4/carbon composites were investigated to achieve a high-rate lithium electrode performance. LiFePO_4/carbon composites were synthesized by a hydrothermal reaction of a solution of FeSO_4 centre dot 7H_2O, H_3PO_4, and LiOHH_2O mixed with carbon powders under nitrogen atmosphere followed by annealing under 1 percent H_2-99 percent Ar atmosphere. Particle size of the obtained LiFePCVcarbon composites observed by scanning electron microscopy was less than 100 nm. At a high current density of 1000 mA g~(-1) the LiFePO_4/carbon composites showed a high discharge capacity of 113 mA h g~(-1), and a flat discharge potential plateau was observed around 3.4 V. The discharge capacity at the high current density, 85 percent of that at a low current density of 30 mA g~(-1) is a quite high value for LiFePO_4 cathodes. Homogeneous microstructure consisting of small particles contributed to the high-rate properties of the LiFePCVcarbon composites.